1. Extending GPS and Galileo interoperability: from frequency/signals to integrity Francisco Salabert Head of GNSS Policy Office DDAS/ EUROCONTROL

2. Presentation Overview
EUROCONTROL and its role on GNSS
Use of GNSS in aviation applications and GNSS policy
Interoperability on GNSS
Extending interoperability to integrity
Good afternoon, my name is F. Salabert and I am the Head of the GNSS Policy Office at EUROCONTROL.
First of all, I would like to thank the organization for giving us the opportunity to share with you the views of EUROCONTROL Agency on the transition to a multiconstellation GNSS in aviation.

3. EUROCONTROL, the European organization for the Safety of Air navigation
A civil and military organisation which currently numbers 38 Member States.
Primary objective is to ensure safety in the development of a seamless, pan-European Air Traffic Management (ATM) system to cope with capacity needs and environmental aspects.
Core business processes:
Harmonise and integrate Air Navigation services aiming at having a “Single Sky” in Europe.
SESAR: Research, design and implementation of the future air traffic management (ATM) network across the European continent.
Pan-European functions (e.g. Flow Control)
Provision of regional ATC services
Support to EU regulation and system performance review
Partnership with European and international stakeholders (e.g. EC, ICAO, FAA,…)
More information:
EUROCONTROL is a civil and military organisation that has 38 Member States. The Agency has around 2500 staff in 7 sites and our Head Quarters are in Brussels.
Our mission is to ensure safety in the development of a seamless, pan-European Air Traffic Management (ATM) system to cope with capacity needs and environmental aspects.
EUROCONTROL was created 40 years ago…and year by year air traffic grows being safety still our first priority. In average there are flights/day in Europe, that means more than 10Million flights per year !! One of our functions is to provide a pan european flow and capacity management to handle all this traffic.
Other main activity is to lead the European Air traffic management (ATM) network in cooperation with aviation stakeholders. In this area SESAR is our flagship project that we are developing in partnership with the EC.
Apart from that, EUROCONTROL operates the regional Air traffic Control centre based in Maastricht.
You can find more information in our website.

4. EUROCONTROL role on GNSS
Long term involvement on GNSS matters
EUROCONTROL is contributing to the development of GNSS applications addressing different aspects:
Safety
Technical
Operational
Economic
Institutional
Legal
Security
Focal point in the definition of the needs of aviation regarding GNSS
Playing a major role in the operational validation of GNSS performance according to aviation requirements.
EUROCONTROL started to work on GNSS 25 years ago…, in the 80s we participated in the ICAO Committee which defined that the future of civil aviation systems should be based on Satellite technologies.
Since then, EUROCONTROL has been contributing to the development of GNNS applications covering :
Safety, Technical, Operational , Economic , Institutional , Legal and Security aspects.
We have specific groups and task forces with our aviation stakeholders where all these aspects are addressed.
EUROCONTROL is the focal point in the definition of the needs of aviation regarding GNSS
In EGNOS Programme, EUROCONTROL is member of the European Tripartite Group with the EC and ESA.

5. Overall use of GNSS in aviation applications
Civil domain
Surveillance (ADS-B)
Navigation
Airport
operations
Timing
This slide shows the use of GNSS in different applications.
Navigation is the most known application in aviation but they are others:
Today surveillance is mainly based on Radars but Automatic Dependent Surveillance Broadcast or ADS-B based on GNSS, is being progressively introduced.
How ADS-B works? Aircraft compute their position based on GNSS and send this information to the Air Traffic Control center or to other aircraft. Air traffic Controllers can see in their screens the position of aircraft with much more accuracy than with a radar. ADS B is very useful in Oceanic areas where there is poor Radar coverage and will contribute to rationalized the network of radars in the long term.
Eurocontrol has an implementation Program called CASCADE to introduce ADS-B in Europe in partnership with Airlines
Other example is the use of GNSS for airport operations. Runways management systems and the surveillance of aircraft and other airport vehicles based on GNSS, can reduce the number of runways incursions.
Apart from the positioning data, GNSS is used as a timing source. We do not need a precision of nanoseconds but we do need to have a common time reference to synchronize systems and operations and GNSS is the best way to do it.
EUROCONTROL is a civil and military organization because civil and military traffic share the Airspace. In the military domain, our objective is to support the use a combined GPS PPS and Galileo PRS receiver that can be certified according to both civil and military requirements.
Military domain (based on GPS PPS & Galileo PRS)

6. Use of GPS in European aviation today
Around 70 % of flights are made by aircraft equipped with GPS/RAIM.
GPS offers a very efficient and free service nominally…..but current GNSS based on GPS only has some deficiencies impeding its comprehensive use in aviation:
single system/operator
single frequency
low power signals
number of satellites
lack of sufficient guarantees
The use of GPS is authorized in Europe since 1998 (for some operations and under certain conditions) based on a Safety assessment, the existence of ICAO Standards and a letter with a political commitment sent from the US government to ICAO.
Safety Case relies upon reversion to conventional means.
We are not starting from scratch, GPS is widely used in aviation (around of 70% of flights in ECAC are done by aircraft equipped with GPS) and in nominal conditions GPS offers a good service that is free of charge.
The use of GPS with RAIM is authorized in Europe since 1998 based on a Safety assessment that relays on reversion to conventional navids. Different type of operations are approved in European States due to institutional concerns.
Having a GNSS based on GPS only has some technical limitations impeding its comprehensive use in aviation:
single system/operator
single frequency
low power signals
number of satellites
The future multiconstelation and multi frequency GNSS environment will overcome most of this deficiencies and is the basis of the GNSS policy that I will present later on.

7. Transition to GNSS in European aviation
Operational needs
More capacity to cope with increasing traffic demands
Improve safety
Reduce environmental impact
Less costs
In line with :
ICAO global strategy
SESAR Master Plan
Technical Realisation
More flexible routes (e.g. RNAV)
Mode demanding performance ( e.g. Integrity, Accuracy,..).
Safety (e.g. Vertical guidance in approaches)
Better surveillance capabilities (ADS-B) to reduce separations
Improved low visibility operations
Common and accurate time reference
Infrastructure
Transition to a multiconstelation GNSS

8. GNSS policy for Navigation applications in civil aviation
Gradual reliance on GNSS for all phases of flight as it will become more robust progressively.
A multi-constellation and multi-frequency GNSS environment in Galileo signals will be used in combination with GPS and other GNSS components to have:
Better performance (accuracy, availability, continuity and integrity).
More robustness against vulnerabilities.
User receivers will process signals from different GNSS constellations in diverse frequency bands in combination with augmentations, depending on individual business cases and the phase of flight.
Final goal is its use as sole service to the extent that this can be shown to be the most cost beneficial solution and if supported by successful safety and security analyses.
A rationalised terrestrial infrastructure must be retained for the foreseeable future.
Now, I will present the GNSS policy for Navigation applications.
During these 3 days in Toulouse, we have seen many presentations
about the expected evolution of GNSS systems. GNSS will provide better performance every year and aviation will have more confidence on GNSS progressively.
Our vision is based on the use of multiconstellation multi frequency signals that will be combined at user level.
Galileo signals will increase overall GNSS robustness and we plan to use Galileo signals in combination with GPS and other GNSS components.

9. The scene: GNSS developments and aviation
New RAIM
capabilities
Galileo
GBAS CAT I
GBAS CATIII
WAAS
EGNOS
Galileo :
Galileo :
FOC ( 30
operational SVs
End of IOV ( 4
operational SVs ) )
COMPASS
COMPASS :
COMPASS
Beidou FOC ( 5
SVs ) )
GPS
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
GPS :
GPS :
GPS :
GLONASS 1 st
Block IIR - M 24
Block IIR - M + II -
F SVs 30
Block III SVs ( 2 nd
civil signal ) ( L 2
C FOC ) (
GPS III FOC )
GPS :
GPS :
GPS : 1 st
Block IIF launch 1 st
Block III launch 24
Block II - F +
Block III SVs ( 3 rd
civil signal ) ( 3 rd
generation GPS ) ( L 5
FOC )
GLONASS :
GLONASS :
GLONASS :
GLONASS : 18
active satellites 24
active satellites
M programme ends
KM programme to start (
MOC ) (
FOC ) ( 2 nd
civil signal )
1) Share a GNSS baseline
2) Extending interoperability
to integrity
3) Define a Multi-constellation receiver
architecture:
Robustness vs Complexity/costs
a) Moving schedule and many uncertainties !
b) Many potential combinations of Signals, constellations
and augmentations (SBAS, GBAS, RAIM, INS,…)
c) A new GNSS configuration every 2-3 years …
whereas aviation equipment has very long lifecycle
and very high installation &certification costs
d) Different integrity schemes/concepts not always compatible. (
FOC )

10. GNSS components and interoperability level
Constellations:
GPS, Galileo, GLONASS, COMPASS, QZZS,…
States level agreements (e.g. US- EU agreement)
ICAO standards
Interoperability Working Group
Standardisation bodies ( RTCA, EUROCAE,..)
SBAS ( WAAS EGNOS, MSAS)
GBAS (CAT I and CAT II/III)
On board augmentations (e.g. RAIM)
and receivers

11. Why interoperability is important for aviation ?
Aviation is a global business and interoperability is a key element
to enable:
Global harmonisation
Standardisation process
Reduce avionics costs (installation, certification,…)
Seamless navigation performance
ICAO standards (SARPS) ensure global interoperability of aviation systems like SBAS and GBAS:
A SBAS receiver that works in the US (WAAS) will work in Europe (EGNOS)
Same aircraft can use a GBAS station in Australia, Brazil, US or Europe.
WAAS
EGNOS
GBAS
GBAS
GBAS
GBAS

12. GNSS components and integrity
GNSS constellations
GPS, Galileo, GLONASS and COMPASS
ABAS
(Aircraft Based
Augmentation System)
RAIM and Inertial systems
This slide shows the main GNSS components in aviation according to aviation terminology. ICAO develops worldwide standards for these components to ensure global interoperability that is essential in a global business like aviation.
There are standards for GPS and GLONASS, and Galileo standards are under preparation. As far as I know, China has not approached yet ICAO to initiate the standardization process of COMPASS.
ABAS are On Board Augmentation systems like Inertial systems or RAIM.
GBAS are local augmentations that are needed for landing in very low visibility conditions at airports
SBAS systems are regional augmentations systems like EGNOS or WAAS.
SBAS (Satellite Based Augmentation System)
WAAS, EGNOS, MSAS, GAGAN,…
GBAS (Ground Based Augmentation System)

13. Why we need to extend interoperability to integrity ?
Initial ideas for early discussion. External consultation need to be established among stakeholders
Aviation welcomed the agreement between US and Europe. It is focused on
frequencies /signals, time offset and security aspects. Integrity aspects are not covered.
2) GNSS integrity is key for aviation safety. Aviation needs interoperability worldwide.
Integrity will become more complex in a multi frequency multi constellation environment. Different integrity mechanisms and concepts exist but are difficult to be combined at user receiver level in an efficient way:
SBAS integrity (applied at regional level). Potential extension to Galileo
GBAS integrity (applied at local level. Extension to Galileo to support CAT II/III operations)
RAIM integrity concepts and new capabilities (Detection of multiple failures, RRAIM, ARAIM,..)
Galileo SoL integrity concept
GPS III integrity concept
4) Integrity is one of the drivers for GNSS systems architectures. There is a need to define a cost effective allocation of integrity burden between constellations, augmentations and user receiver.
GEAS study is assessing architectures to provide LPV 200 worldwide based on GPS (GIC, RRAIM and ARAIM ). Phase I of GEAS study is based on GPS only, could consider Galileo in future work.
Galileo SoL is being defined to provide LPV 200 worldwide based on Galileo only.
Interoperability is not detrimental to independence.
5) Lack of an agreed GNSS baseline on integrity could delay transition to GNSS.
6) There is a risk of having different receivers standards at regional level.

14. How to extend interoperability to integrity ?
Initial ideas for early discussion. External consultation need to be established among stakeholders
Goal: Promote and harmonise integrity concepts and mechanisms that can be applied at user level worldwide.
Recommendation. To reinforce international cooperation at different levels:
US–EU at programme and political level to assess interoperability between GPS and Galileo at integrity level.
Coordination between GPS evolution studies (e.g. GEAS) and European activities.
Assess the impact of changing/adapting (on-going and future) technical concepts/developments to improve interoperability.
IWG (Interoperability Working Group) for SBAS developments
Share a GNSS baseline and a transition path between FAA and EUROCONTROL. Coordination between GNSS baseline in SESAR and Next Gen
5. Support ICAO standardization processes for global interoperability in aviation
6. Promote cooperation between RTCA and EUROCAE for receivers standardization

15. QUESTIONS ?